Various fixed couplings are known for high-pressure hoses, particularly for connecting hoses reinforced with metal inserts. The most frequently used couplings of that are those having pressed, bound and/or screwed connections. A common characteristic of such connections is that to achieve safe sealing and connection, a higher pressure must prevail in course of installation on the surface of element arranged in the inside of the hose than the prevailing pressure which may occur in use.
U.S. Pat. No. 3,347,571 discloses a pressed connecting structure, U.S. Pat. No. 1,576,764 discloses a screwed connection, and German Federal Republic Pat. No. 1,223,209 relates to a bound connection.
Couplings fixed by gluing are disclosed for example in Hungarian Pat. No. 168,837, French Pat. No. 2,214,852 and British Pat. No. 2,088,506 and are considered to be the most modern ones in comparison to the aforementioned structures.
However, in the case of glued connections, if one can deal at all with the problem of building up the hoses, that it would require a most complicated coupling device and installation would require a greater expenditure of labor. A further problem is that welding of the special connectors and hose couplings having a large diameter cannot be realized in all cases.
Generally couplings of large diameter highly loadable hoses are assembled while the hoses are being built up and if the hoses are based on some elastomer then vulcanization is carried out after assembling the hose with the coupling. For example, couplings of every marine oil inlet and racking hose are made in this manner. With couplings to be installed during the building up and when the dimension of the final product are known in advance, hoses cannot be produced in greater length for the purpose of storage. Row elements below the rigid connecting element are vulcanized without applying pressure or at medium pressures and, therefore, bubbles and delamination of layers can often take place.